Dontcheff

Database Magic with Oracle Database 12c

In Database options, Oracle database on November 28, 2016 at 09:40

“Science is magic that works” Kurt Vonnegut

magic

Have a look at the following series of commands.

A query on the SALES table takes normally more than 2 minutes but setting the database_performance parameter to SUPER_FAST makes it … as expected super fast: less than 1 second. Setting the database_performance parameter to SUPER_SLOW makes the query hang. Again “as expected”.

sqltf

So, how come all this is possible?

Before blogging it, I showed this “magical trick” to 100s of people: at Oracle OpenWorld, at some Oracle User Group events and conferences and to many DBAs. Here is the explanation.

Behind the curtains, I am using the Oracle SQL Translation Framework.

exec dbms_sql_translator.create_profile('OOW');

select object_name, object_type from dba_objects where object_name like 'OOW';

exec dbms_sql_translator.register_sql_translation('OOW',
'SELECT max(price) most_expensive_order from sales',
'SELECT max(price) most_expensive_order from julian.sales')
/

exec dbms_sql_translator.register_sql_translation('OOW',
'alter session set database_performance="SUPER_FAST"',
'alter session set inmemory_query="ENABLE"')
/

exec dbms_sql_translator.register_sql_translation('OOW',
'alter session set database_performance="RATHER_SLOW"',
'alter session set inmemory_query="DISABLE"')
/

exec dbms_sql_translator.register_sql_translation('OOW',
'alter session set database_performance="SUPER_SLOW"',
'begin uups; end;')
/

The procedure uups is just helping us mimic a never ending loop:

create or replace procedure uups
as  
 x date;
 BEGIN
   LOOP
     BEGIN
       SELECT null INTO x FROM dual WHERE sysdate = sysdate;
     EXCEPTION
       WHEN NO_DATA_FOUND THEN EXIT;
     END;
   END LOOP;
 END;
/

Then, once connected to the database as SYS you run the following commands:

set timing on

alter session set sql_translation_profile = OOW
/

alter session set events = '10601 trace name context forever, level 32'
/
 

The last question now is probably what changes the performance? But this should be clear from the usage of the inmemory_query parameter. I am simply keeping the SALES table in memory. So yes, the in-memory option can be 137 times faster! 133.22/0.97 ~ 137

Here is something more to read if you find the topic interesting:

SQL Translation Framework in Oracle Database 12c by Okcan Yasin Saygili
SQL Translation Framework by Kerry Osborne
Oracle 12c Security – SQL Translation and Last Logins by Pete Finnigan

  1. We must remember security issue regarding SQL Translation Framework , we can easily delete data instead of select.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: